Steve, I'm currently building a new house. I asked my builder and structural engineer about the underfloor insulation. The engineer said the "up-turn" piece as you call it would weaken our foundation. We are putting insulation under the floor but not where the slab butts with the walls & footings. BTW, we are building to Fortified Gold standards in the mountains.
I’m totally sold! I have your videos running on RU-vid and my copy of Pretty Good House in my lap. When I retire from the military next year I’m going to commission a design for a build in PA. I hope your firm doesn’t grow too much! (for strictly selfish reasons)
When you specify the vapor barrier, do you also specify that all the seams and pipe penetrations get taped by a long-life stick tape? Something like Stego tape comes to mind for making sure that moisture and radon do not crawl through the gaps and overlaps. In addition to the edge detail where you have it taped continuous with the wall insulation, I'm more thinking about the long roll seams and around the pipes and columns. Concrete contractors are notorious for breaking those tape points and putting holes in the vapor barrier. I had a concrete placing team tell me that I had to put a no-holes or no-payment clause in the contract to get their team to really, really pay attention.
Check out WWPI's document (pdf) "Effective Termite Protection for Multi-Family & Commercial Wood Buildings". Besides the usual water management and air barrier continuity practices, you utilize PT wood for ground contact, optionally borate spray treat the bottom 2-4' of basement/level 1 exterior wall framing. You can also use mechanical barriers like marine-grade steel mesh. I've had subt. termites here in my 1950's house. Never again. 😅
